1. Field of the Invention
The present invention relates to a field effect transistor, in which a diamond is used as a semiconductor material so that it can stably operate in a high-temperature environment and tolerate high-output operations, and a method of making the same.
2. Related Background Art
Conventionally, in order to develop a semiconductor device which can stably operate in a high-temperature environment and tolerate high-output operations, it has been attempted to use, as a semiconductor material, a diamond synthesized in a vapor phase.
Diamonds have a band gap as large as about 5.5 eV, they do not have an intrinsic region, where conduction of carriers cannot be controlled any more, at a temperature below about 1,400.degree. C. Also, since their permittivity is as low as about 5.5, they have a breakdown electric field as high as about 5.times.10.sup.6 V.multidot.cm.sup.-1. Further, they have a large carrier mobility, in particular, such that their electron mobility and hall mobility at a temperature of about 300 K are about 2,000 cm.sup.2 .multidot.V.sup.-1 .multidot.s.sup.-1 and about 2,100 cm.sup.2 .multidot.V.sup.-1 .multidot.s.sup.-1, respectively. Accordingly, a semiconductor device made of a diamond can be expected to operate with a high frequency and a high output at a high temperature.
For example, a diode having a good rectification characteristic, a high pressure resistance, and an excellent temperature-stability has been made by using a diamond. The prior art in this regard is disclosed in detail in Japanese Unexamined Patent Publication No. 3-278474, No. 4-22172, No. 4-293272, No. 4-293273, and No. 4-302172, "Jpn. J. Appl. Phys., vol. 29, no. 12, pp. L2163-L2164, 1990," and the like.
Also, by applying this technique, a diamond is used to form a transistor having an improved operation characteristic. The prior art in this regard is disclosed in detail in Japanese Unexamined Patent Publication No. 4-354139, No. 5-29608, No. 5-29609, and No. 5-29610, "Proceedings of The Second International Conference on New Diamond Science and Technology (Washington, D.C.), Materials Research Society (Pittsburgh, Pa.), pp. 975-1000, 1990," and the like.